Continued abuse of organic solvents and related substances self-administered by inhalation ("glue-sniffing") makes it imperative to develop a laboratory model of these phenomena. Squirrel monkeys (Saimiri sciurea) are being studied to determine the conditions under which they will self-administer such substances (for example, nitrous oxide and toluene). Exposure concentration, exposure duration, schedule of delivery, and chronicity are among the variables whose contribution will be assessed. Concurrently, behavioral toxicity is evaluated in a program that includes pigeons and rodents as well as primates, and a wide range of performance parameters.